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  <section id="generic-operating-system-services">
<span id="allos"></span><h1>Generic Operating System Services<a class="headerlink" href="#generic-operating-system-services" title="Permalink to this headline">¶</a></h1>
<p>The modules described in this chapter provide interfaces to operating system
features that are available on (almost) all operating systems, such as files and
a clock.  The interfaces are generally modeled after the Unix or C interfaces,
but they are available on most other systems as well.  Here’s an overview:</p>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="os.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">os</span></code> — Miscellaneous operating system interfaces</a><ul>
<li class="toctree-l2"><a class="reference internal" href="os.html#file-names-command-line-arguments-and-environment-variables">File Names, Command Line Arguments, and Environment Variables</a></li>
<li class="toctree-l2"><a class="reference internal" href="os.html#process-parameters">Process Parameters</a></li>
<li class="toctree-l2"><a class="reference internal" href="os.html#file-object-creation">File Object Creation</a></li>
<li class="toctree-l2"><a class="reference internal" href="os.html#file-descriptor-operations">File Descriptor Operations</a><ul>
<li class="toctree-l3"><a class="reference internal" href="os.html#querying-the-size-of-a-terminal">Querying the size of a terminal</a></li>
<li class="toctree-l3"><a class="reference internal" href="os.html#inheritance-of-file-descriptors">Inheritance of File Descriptors</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="os.html#files-and-directories">Files and Directories</a><ul>
<li class="toctree-l3"><a class="reference internal" href="os.html#linux-extended-attributes">Linux extended attributes</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="os.html#process-management">Process Management</a></li>
<li class="toctree-l2"><a class="reference internal" href="os.html#interface-to-the-scheduler">Interface to the scheduler</a></li>
<li class="toctree-l2"><a class="reference internal" href="os.html#miscellaneous-system-information">Miscellaneous System Information</a></li>
<li class="toctree-l2"><a class="reference internal" href="os.html#random-numbers">Random numbers</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="io.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">io</span></code> — Core tools for working with streams</a><ul>
<li class="toctree-l2"><a class="reference internal" href="io.html#overview">Overview</a><ul>
<li class="toctree-l3"><a class="reference internal" href="io.html#text-i-o">Text I/O</a></li>
<li class="toctree-l3"><a class="reference internal" href="io.html#binary-i-o">Binary I/O</a></li>
<li class="toctree-l3"><a class="reference internal" href="io.html#raw-i-o">Raw I/O</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="io.html#high-level-module-interface">High-level Module Interface</a></li>
<li class="toctree-l2"><a class="reference internal" href="io.html#class-hierarchy">Class hierarchy</a><ul>
<li class="toctree-l3"><a class="reference internal" href="io.html#i-o-base-classes">I/O Base Classes</a></li>
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<li class="toctree-l3"><a class="reference internal" href="io.html#buffered-streams">Buffered Streams</a></li>
<li class="toctree-l3"><a class="reference internal" href="io.html#id1">Text I/O</a></li>
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<li class="toctree-l2"><a class="reference internal" href="io.html#performance">Performance</a><ul>
<li class="toctree-l3"><a class="reference internal" href="io.html#id2">Binary I/O</a></li>
<li class="toctree-l3"><a class="reference internal" href="io.html#id3">Text I/O</a></li>
<li class="toctree-l3"><a class="reference internal" href="io.html#multi-threading">Multi-threading</a></li>
<li class="toctree-l3"><a class="reference internal" href="io.html#reentrancy">Reentrancy</a></li>
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</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="time.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">time</span></code> — Time access and conversions</a><ul>
<li class="toctree-l2"><a class="reference internal" href="time.html#functions">Functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="time.html#clock-id-constants">Clock ID Constants</a></li>
<li class="toctree-l2"><a class="reference internal" href="time.html#timezone-constants">Timezone Constants</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="argparse.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">argparse</span></code> — Parser for command-line options, arguments and sub-commands</a><ul>
<li class="toctree-l2"><a class="reference internal" href="argparse.html#example">Example</a><ul>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#creating-a-parser">Creating a parser</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#adding-arguments">Adding arguments</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#parsing-arguments">Parsing arguments</a></li>
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<li class="toctree-l2"><a class="reference internal" href="argparse.html#argumentparser-objects">ArgumentParser objects</a><ul>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#prog">prog</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#usage">usage</a></li>
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<li class="toctree-l3"><a class="reference internal" href="argparse.html#parents">parents</a></li>
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<li class="toctree-l3"><a class="reference internal" href="argparse.html#prefix-chars">prefix_chars</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#fromfile-prefix-chars">fromfile_prefix_chars</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#argument-default">argument_default</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#allow-abbrev">allow_abbrev</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#conflict-handler">conflict_handler</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#add-help">add_help</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#exit-on-error">exit_on_error</a></li>
</ul>
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<li class="toctree-l2"><a class="reference internal" href="argparse.html#the-add-argument-method">The add_argument() method</a><ul>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#name-or-flags">name or flags</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#action">action</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#nargs">nargs</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#const">const</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#default">default</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#type">type</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#choices">choices</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#required">required</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#help">help</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#metavar">metavar</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#dest">dest</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#action-classes">Action classes</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="argparse.html#the-parse-args-method">The parse_args() method</a><ul>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#option-value-syntax">Option value syntax</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#invalid-arguments">Invalid arguments</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#arguments-containing">Arguments containing <code class="docutils literal notranslate"><span class="pre">-</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#argument-abbreviations-prefix-matching">Argument abbreviations (prefix matching)</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#beyond-sys-argv">Beyond <code class="docutils literal notranslate"><span class="pre">sys.argv</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#the-namespace-object">The Namespace object</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="argparse.html#other-utilities">Other utilities</a><ul>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#sub-commands">Sub-commands</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#filetype-objects">FileType objects</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#argument-groups">Argument groups</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#mutual-exclusion">Mutual exclusion</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#parser-defaults">Parser defaults</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#printing-help">Printing help</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#partial-parsing">Partial parsing</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#customizing-file-parsing">Customizing file parsing</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#exiting-methods">Exiting methods</a></li>
<li class="toctree-l3"><a class="reference internal" href="argparse.html#intermixed-parsing">Intermixed parsing</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="argparse.html#upgrading-optparse-code">Upgrading optparse code</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="getopt.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">getopt</span></code> — C-style parser for command line options</a></li>
<li class="toctree-l1"><a class="reference internal" href="logging.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging</span></code> — Logging facility for Python</a><ul>
<li class="toctree-l2"><a class="reference internal" href="logging.html#logger-objects">Logger Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#logging-levels">Logging Levels</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#handler-objects">Handler Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#formatter-objects">Formatter Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#filter-objects">Filter Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#logrecord-objects">LogRecord Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#logrecord-attributes">LogRecord attributes</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#loggeradapter-objects">LoggerAdapter Objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#thread-safety">Thread Safety</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#module-level-functions">Module-Level Functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#module-level-attributes">Module-Level Attributes</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.html#integration-with-the-warnings-module">Integration with the warnings module</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="logging.config.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.config</span></code> — Logging configuration</a><ul>
<li class="toctree-l2"><a class="reference internal" href="logging.config.html#configuration-functions">Configuration functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.config.html#configuration-dictionary-schema">Configuration dictionary schema</a><ul>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#dictionary-schema-details">Dictionary Schema Details</a></li>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#incremental-configuration">Incremental Configuration</a></li>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#object-connections">Object connections</a></li>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#user-defined-objects">User-defined objects</a></li>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#access-to-external-objects">Access to external objects</a></li>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#access-to-internal-objects">Access to internal objects</a></li>
<li class="toctree-l3"><a class="reference internal" href="logging.config.html#import-resolution-and-custom-importers">Import resolution and custom importers</a></li>
</ul>
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<li class="toctree-l2"><a class="reference internal" href="logging.config.html#configuration-file-format">Configuration file format</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="logging.handlers.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">logging.handlers</span></code> — Logging handlers</a><ul>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#streamhandler">StreamHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#filehandler">FileHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#nullhandler">NullHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#watchedfilehandler">WatchedFileHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#baserotatinghandler">BaseRotatingHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#rotatingfilehandler">RotatingFileHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#timedrotatingfilehandler">TimedRotatingFileHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#sockethandler">SocketHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#datagramhandler">DatagramHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#sysloghandler">SysLogHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#nteventloghandler">NTEventLogHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#smtphandler">SMTPHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#memoryhandler">MemoryHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#httphandler">HTTPHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#queuehandler">QueueHandler</a></li>
<li class="toctree-l2"><a class="reference internal" href="logging.handlers.html#queuelistener">QueueListener</a></li>
</ul>
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<li class="toctree-l1"><a class="reference internal" href="getpass.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">getpass</span></code> — Portable password input</a></li>
<li class="toctree-l1"><a class="reference internal" href="curses.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">curses</span></code> — Terminal handling for character-cell displays</a><ul>
<li class="toctree-l2"><a class="reference internal" href="curses.html#functions">Functions</a></li>
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<li class="toctree-l1"><a class="reference internal" href="curses.html#module-curses.textpad"><code class="xref py py-mod docutils literal notranslate"><span class="pre">curses.textpad</span></code> — Text input widget for curses programs</a><ul>
<li class="toctree-l2"><a class="reference internal" href="curses.html#textbox-objects">Textbox objects</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="curses.ascii.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">curses.ascii</span></code> — Utilities for ASCII characters</a></li>
<li class="toctree-l1"><a class="reference internal" href="curses.panel.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">curses.panel</span></code> — A panel stack extension for curses</a><ul>
<li class="toctree-l2"><a class="reference internal" href="curses.panel.html#functions">Functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="curses.panel.html#panel-objects">Panel Objects</a></li>
</ul>
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<li class="toctree-l1"><a class="reference internal" href="platform.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">platform</span></code> —  Access to underlying platform’s identifying data</a><ul>
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<li class="toctree-l1"><a class="reference internal" href="errno.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">errno</span></code> — Standard errno system symbols</a></li>
<li class="toctree-l1"><a class="reference internal" href="ctypes.html"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ctypes</span></code> — A foreign function library for Python</a><ul>
<li class="toctree-l2"><a class="reference internal" href="ctypes.html#ctypes-tutorial">ctypes tutorial</a><ul>
<li class="toctree-l3"><a class="reference internal" href="ctypes.html#loading-dynamic-link-libraries">Loading dynamic link libraries</a></li>
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